import sys

sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# inf = (1 << 31)-1
md = 10**9+7
# md = 998244353

n, m = LI()
aa = LLI(n)

if n==1:
    print(0)
    exit()

dp = aa[0][:]
mn = 0
for i in range(1, n):
    ndp = [inf]*m
    nxt = inf
    for j in range(m):
        ndp[j] = min(dp[j], mn+aa[i-1][j])+aa[i][j]
        nxt = min(nxt, ndp[j])
    mn = nxt
    dp = ndp

print(min(dp))